There is known a map display apparatus for a motor vehicle, which displays a road map in the form of a so-called bird's-eye view, namely, displays the road map on a display device such that the road map around the current position of the vehicle (vehicle position) is displayed in a larger scale than a far side view (refer to laid-open Publication No. 2-244188 of unexamined Japanese Patent Application, for example). The apparatus disclosed in the above-identified publication places a view point behind the current position of the vehicle, and displays a view taken by looking down the map from this view point in the travelling direction of the vehicle, on a screen of the display device. In this manner of displaying the bird's-eye view, it is possible to display map information around the current position in a larger scale, and also display a wide range of map information ranging from the current position to a distance place. This makes it easier to visually grasp connecting conditions of junctions of roads. Further, the road map can be displayed with an increased sense of reality as if the driver himself/herself actually looked down the road map.
When the road map is displayed in the form of the bird's-eye view, however, the map scale is continuously varied from the lower edge of the screen toward the upper edge, making it difficult for the driver to grasp a sense of distance. When the driver is not accurately aware of road conditions around the vehicle position, as in the case where the vehicle is running through an area that is unfamiliar to the driver, it is more desirable to display an ordinary planimetric map on a map scale that does not vary in local parts of the map, rather than displaying the bird's-eye view.
If the processing for displaying the road map in the form of the bird's-eye view is effected using road map data independent of road map data used for displaying a planimetric map, there arises a need to newly add the road map data for the bird's-eye view, which may increase the cost of the apparatus.
It is an object of the present invention to provide a map display apparatus for a motor vehicle, which is capable of selecting as desired the map form of the road map displayed on the display device. It is another object of the present invention to provide a map display apparatus for a motor vehicle, which is able to display road maps in a plurality of different map forms at the same time. It is a further object of the present invention to provide a map display apparatus for a motor vehicle, which is able to display road maps of different map forms, using the same map data base.